The present invention pertains to a coated cutting insert, and especially a coated cutting insert coated via a chemical vapor deposition (CVD) technique, and which is useful in chipforming material removal applications such as, for example, machining, turning, and milling, as well as a method of making the same. More specifically, the present invention pertains to a CVD-coated cutting insert comprising a substrate with a coating scheme thereon and wherein the coating scheme includes a plurality of coating layers including a multi-layered coating scheme comprising a plurality of repeating coating sets. Each coating set comprises a coating layer of aluminum oxide and a coating layer of a nitrogen-containing material (e.g., titanium aluminum oxynitride or titanium nitride or zirconium nitride) whereby the coating scheme, which is applied by CVD, has higher toughness, good crack resistance, acceptable adhesion properties, acceptable abrasive wear resistance properties, and acceptable edge integrity, as well as a method of making the coated cutting insert.
Heretofore, coated bodies, such as, for example, coated cutting inserts, have been used in chipforming material removal applications. Such coated cutting inserts typically comprise a substrate of a cutting insert geometry and a coating scheme on the substrate. The coating layers that comprise the coating scheme typically comprise hard refractory materials that exhibit the property of wear resistance. One primary purpose of using a coating on a cutting insert has been to lengthen the useful life of the cutting insert in the material removal application. Exemplary ones of these coating schemes using hard refractory materials are described in the following documents: European Patent Application 1 245 698 B1 to Mitsubishi Materials Corp., European Patent Application No. 1 455 003 A2 to Sandvik A B, European Patent Application No. 1 980 649 B1 to Iscar Ltd., United States Published Patent Application No. US2012/0202032 to Tatsuoka et al., United States Published Patent Application No. US2013/0045057 to Kojima et al., U.S. Pat. No. 7,132,153 to Zackisson et al., U.S. Pat. No. 7,396,371 to Cedergren et al., U.S. Pat. No. 7,455,918 to Gates, Jr. et al., U.S. Pat. No. 7,470,296 to Londholm et al., U.S. Pat. No. 7,597,951 to Bjormander et al., U.S. Pat. No. 7,727,592 to Cedergren et al., U.S. Pat. No. 7,785,665 to Gates, Jr., et al., U.S. Pat. No. 8,080,312 to McNerny et al., U.S. Pat. No. 8,080,323 to Ban et al., U.S. Pat. No. 8,323,783 to Sottke et al., U.S. Pat. No. 8,557,406 to Ban et al., Chinchanikar et al., “Wear behavior of single-layer and multi-layer coated carbide inserts in high speed machining of hardened AISI 4340 steel”, Journal of Mechanical Science and Technology, 27 (5), (2013), pp. 1451-1459, and Halvarsson et al., “Microstructure and performance of CVD κ-Al2O3 multilayers”, Materials Science and Engineering, A209 (1996) pp. 337-344.
As is apparent from the above documents, many different coating schemes for a coated cutting insert have been used in the past. According to these documents, each one of these coating schemes is supposed to provide certain advantages. Even though there have been coating schemes that are supposed to provide certain advantages, there remains a need to provide coating scheme that lengthen the useful life of a coated cutting insert, as well as to improve the performance characteristics of a coated cutting insert in a material removal application. Further, there remains a need to provide an improved coated cutting insert wherein the coating scheme has a high toughness resulting in better edge integrity, especially during heavily interrupted turning and milling operations. Still further there remains a need to provide an improved coated cutting insert that has a coating scheme which includes a multi-layered coating scheme that better inhibits crack growth and propagation in the coating scheme whether due to mechanical stresses or thermal cycling. Yet further, there remains a need to provide an improved coated cutting insert that includes a transition coating layer that functions to promote better nucleation and adhesion of the multi-layered coating scheme.
Therefore, it would highly desirable to provide an improved coated cutting insert, and a method of making the same, wherein the cutting insert is useful in material removal applications. It would be highly desirable to provide an improved coated cutting insert, and a method of making the same, wherein the cutting insert is useful in material removal applications wherein the coated cutting insert exhibits a lengthened tool life. It would be highly desirable to provide an improved coated cutting insert, and a method of making the same, wherein the cutting insert is useful in material removal applications wherein the coated cutting insert exhibits improved performance characteristics.
It would be highly desirable to provide an improved coated cutting insert, and a method of making the same, wherein the cutting insert is useful in material removal applications wherein the coated cutting insert has a coating scheme with a high toughness resulting in better edge integrity, especially during heavily interrupted turning and milling operations. It would be highly desirable to provide an improved coated cutting insert, and a method of making the same, wherein the cutting insert is useful in material removal applications wherein the coated cutting insert has a coating scheme which includes a multi-layered coating scheme that better inhibits crack growth and propagation in the coating scheme whether due to mechanical stresses or thermal cycling. It would be highly desirable to provide an improved coated cutting insert, and a method of making the same, wherein the cutting insert is useful in material removal applications wherein the coated cutting insert has a coating that includes a transition coating layer that functions to promote better nucleation and adhesion of the multi-layered coating scheme.